It’s red carpet season in Hollywood and industry-show season on Wall Street, and the events are spotlighting the most famous women in film and business.

While Amy Adams and Cate Blanchett received rave reviews for their fashion finesse, the two most famous female CEOs in the nation, Marissa Mayer of Yahoo! and Mary Barra of General Motors, got very different manage­ment-performance reviews as the klieg lights turned upon them.

And while it may sound sexist to focus on these executives, for investors there are plenty of lessons to be learned from the two women who broke that thick glass ceiling that covers both Detroit and Silicon Valley.

Not only do the two companies trade at just around $40 a share, but they also are both former American icons trying to reinvent themselves. Their combined market value tops $90 billion.

So who’s wearing it best? Right now, Yahoo!’s Mayer might want to take a few lessons from GM’s Barra. Here they are:

• Don’t court the fashion cameras. While Barra is sure to be the main attraction as the Detroit auto show opens to the public this weekend, so far she has wisely resisted the call of a Vanity Fair photo shoot.

• Love every part of your company. Although Mayer has struggled with Yahoo!’s chief challenge — namely, ad revenue — admitting she knows little about it and then in the course of a year hiring and firing the guy she put in charge, Barra embraces everything GM.

A company lifer who most recently headed up product design, she gushed in November that she had the best job in the place.

It’s impossible to imagine Mayer swooning over the Yahoo! homepage the way Barra does over a vintage Camero.

Time will tell if Mayer will fulfill her promise in the Yahoo! job. If she takes a few tips from Mary Barra, she may still have a fighting chance.